zkt25/assignment2/README.md

Weather Web App - Kubernetes Deployment

This project deploys a full-stack weather web application to Kubernetes. It includes:

• A frontend website to search weather by city
• A backend PostgreSQL database for logging searches
• A Node.js API to connect the frontend to the database

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Application Description

• Frontend (weather.html): A responsive, modern web UI that shows current weather data using the OpenWeatherMap API.
• Backend (PostgreSQL): Stores weather search history via a weather_log table.
• API Server (Node.js): Receives weather data from the frontend and logs it to the PostgreSQL database.

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Containers Used

Container	Image	Description
weather-frontend	Custom Nginx-based	Serves the weather.html UI
postgres	postgres:15	Provides relational database backend
weather-api	Custom Node.js	API that logs weather data to PostgreSQL

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☸️ Kubernetes Objects

Object Type	File	Description
Namespace	(inside script)	Isolates resources under webapp-ns
Deployment	deployment.yaml	Manages frontend app
Deployment	deployment-api.yaml	Manages the Node.js API
StatefulSet	statefulset.yaml	Manages PostgreSQL instance with persistent volume
PersistentVolume	statefulset.yaml	Host-mounted volume for PostgreSQL data
PersistentVolumeClaim	statefulset.yaml	Requests storage for StatefulSet
Service	service.yaml	Exposes frontend via NodePort
Service	deployment-api.yaml	Exposes API via NodePort
ConfigMap	Created by script	Stores init-db.sql used to create the weather_log table

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Networking & Volumes

Virtual Networks:

• Kubernetes handles inter-service communication via internal DNS and ClusterIP services.
• Frontend and backend are externally reachable using NodePort services.

Volumes:

• PersistentVolume and PersistentVolumeClaim ensure PostgreSQL data is retained.
• ConfigMap mounts the SQL init script for PostgreSQL setup.

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⚙️ Container Configurations

Frontend

• Dockerfile uses nginx:alpine
• Serves weather.html (renamed as index.html inside container)
• Exposed on port 80

Node.js API

• Built with Node.js 18
• Listens on port 3000
• Connects to PostgreSQL using service DNS
• Accepts POST requests at /log with weather data

PostgreSQL

• postgres:15 with weatheruser, weatherpass, and weatherdb
• Init script creates a weather_log table with a sample row

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How to Use the Application

1. Build Docker Images

./prepare-app.sh

2. Start the App (create namespace and apply all configs)

./start-app.sh

3. View the App

minikube service weather-service -n webapp-ns

Or get the NodePort manually:

kubectl get svc -n webapp-ns
minikube ip

Then open:

http://<minikube-ip>:<frontend-nodeport>

4. Use the App

• Enter a city
• Weather will be shown
• Data is logged in PostgreSQL automatically

5. Stop and Clean Up

./stop-app.sh

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API Key Setup

• Register at OpenWeatherMap
• Get your free API key
• Replace the placeholder in weather.html:

const apiKey = "YOUR_API_KEY";

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Conclusion

• Frontend calls OpenWeatherMap and logs data to your backend
• PostgreSQL is prepped with a table to store queries
• You can expand the API to serve saved data or stats